The present invention relates to a structure for installing a viscous vibration-damping wall and a method of installing the same, and more particularly to a structure for installing a viscous vibration-damping wall whose connecting structure is simple and which, while possessing a sufficient withstanding force, can be manufactured at low cost by making improvements on the structure for installing the viscous vibration-damping wall on a main frame structure, as well as a method of installing the same.
Measures for enhancing the damping performance of structures have been adopted since ancient times to enhance the safety of earthquake resistance of building structures and improve the dwelling ability of structures against the wind and other dynamic external forces. As specific solutions therefor, viscous vibration-damping walls have been put to practical use, and the number of the viscous vibration-damping walls actually adopted has been on an increasing trend in recent years.
The viscous vibration-damping wall is constructed such that an upper-end open housing, which is formed by a pair of steel-made side plates mounted on a base plate and a pair of flange plates disposed on both sides of the pair of side plates, is integrated with a lower-floor girder, an intermediate plate integrated with an upper-floor girder is inserted in it, and a viscous material or a viscoelastic material is placed in the gap therebetween with a predetermined thickness.
To build the vibration-damping wall, connection to a main frame structure is required, but under the present circumstances connection metal plates from the main frame structure for connection to the viscous vibration-damping wall include a large number rib plates and make the joints complex, constituting a factor for higher cost.
Referring to FIG. 7, a description will be given of the connection between a conventional viscous vibration-damping wall and the main frame structure. A base plate 32 of a housing 31 making up a vibration-damping wall 30 is bolted to a flange surface of a rising metal plate 34 disposed on a lower-floor girder 33, while an intermediate plate 35 of the vibration-damping wall has a top plate 36 welded to its tip portion and is bolted to a flange surface of a mounting plate 38 disposed on an upper-floor girder 37.
In this state, when the vibration-damping wall 30 bears a horizontal force due to an external force, bending moment due to the borne shearing force occurs in the top plate 36 and the base plate 32 at the upper and lower ends.
The stress applied to the joints acts as the horizontal shearing force with respect to the bolts at the plane of connection, and at the same time a vertical axial force which is distributed widely at the edge portions of the vibration-damping wall 30 occurs in the bolts at the plane of connection due to the bending moment. As a result, large bending stresses occur in the top plate 36 and the base plate 32 having bolt hole portions arranged horizontally, so that it is necessary to adopt countermeasures for the respective plates.
Consequently, as shown in the drawing, a multiplicity of vertical rib plates 39 and 40 are fixed to the base plate 32 and the top plate 36 as well as the rising metal plate 34 and the mounting plate 38 corresponding thereto, and large-scale reinforcement is provided particularly at the edge portions of the vibration-damping wall. This results in an enormously large increase in cost, and constitutes a hindrance to the connection to a member perpendicular to a girder, and to through holes of sleeves of the facility.
Since the damping performance which can be added to a structure is proportional to the quantity of vibration-damping walls that are installed, it is desirable to adopt a large number of vibration-damping walls. However, since the cost required in the installation is also proportional to the quantity used, it is an important problem to reduce the cost of the building construction of the vibration-damping walls and to prevent adverse effects from being exerted on other execution of works.
To overcome this problem, a method of building construction has been proposed in which all the upper and lower flange portions are removed. (Refer to JP-A-10-46865)
In this proposal, as shown in the drawing, a bolting steel plate 52 is provided which has the same thickness as an inner wall steel plate 51 of a vibration-damping wall 50 to be fixed to the underside of an upper-floor girder or a reinforced portion thereof, and the inner wall steel plate 51 of the vibration-damping wall is disposed immediately therebelow. A pair of bolting reinforcing plates 53 are disposed on both sides of the inner wall steel plate 51, and the three steel plates are tightened by high-strength bolts 54 so as to be integrated.
In addition, on a lower floor side, a bolting lower steel plate 56 is welded in advance to lower sides of a pair of outer wall steel plates 55 of the vibration-damping wall, and a steel plate 57 of the same thickness as the bolting lower steel plate 56 is provided on a lower-floor girder, and is integrated therewith in the same way as the upper side.
An assertion is made that it is possible to substantially reduce the cost required for the overall building construction of the vibration-damping wall, since the mechanism for transmitting the stress can be rationalized and the fabrication of the vibration-damping wall itself and the fixing portions can be both simplified by virtue of the construction in which flanged connection in each of the upper and lower portions is eliminated, as described above.
However, with the vibration-damping wall according to this proposal, the vibration-damping wall itself is specially provided with the bolting lower steel plate, the inner wall steel plate is provided with an upper reinforced portion, and the friction-type high-strength bolted connection for jointing adopts a structure in which a multiplicity of bolts are arranged on end portion sides of the vibration-damping wall. Such a construction is a natural consequence of the fact that the bolting lower steel plate and the inner wall steel plate need to simultaneously withstand both the shearing force and the tensile force with respect to the bending moment occurring in the vibration-damping wall. A substantial thickness must be inevitably secured for the bolting lower steel plate, so that the cost of the vibration-damping wall itself is not much different from other conventional vibration-damping walls.
In addition, concerning the handling of the vibration-damping wall, since the structure adopted is such that the vibration-damping wall cannot be self-supported, special attention is required for safety and workability under the circumstances of transportation, storage, and on-site setting.
The present invention provides a structure for installing a viscous vibration-damping wall which is simple while possessing a sufficient withstanding force, and which can be manufactured at low cost by making improvements on the structure for connection at the time of installing the viscous vibration-damping wall on a main frame structure, as well as a method of installing the same.
The structure for installing a viscous vibration-damping wall in accordance with the present invention is basically a structure for installing a viscous vibration-damping wall in which a housing with its upper end open is formed by uprightly setting a pair of steel-made side plates on a base plate and by disposing a pair of flange plates on both sides of the pair of side plates, an intermediate plate is inserted in the housing, and a viscous material or a viscoelastic material is placed in its gap portion, characterized in that a flange of a lower-floor girder is provided with base-plate connecting hole portions and a pair of flange connecting plates, and the base plate and the flange plates are connected thereto, and the intermediate plate is directly connected to a gusset plate fixed to a flange of an upper-floor girder. Specifically, the structure for installing a viscous vibration-damping wall is characterized in that a rising metal plate is fixed on the flange of the lower-floor girder, and the base-plate connecting hole portions and the pair of flange connecting plates are provided on the rising metal plate, that the connection between the flange plate and the flange connecting plate is one-plane friction-type high-strength bolted connection, and that the direct connection between the intermediate plate and the gusset plate is one-plane friction-type high-strength bolted connection or two-plane friction-type high-strength bolted connection using a pair of splicing plates.
By virtue of the above-described structure, the top plate, the brackets, and the reinforcing rib plates at various portions which have been used in the building construction of the vibration-damping wall are made substantially unnecessary, the reduction of the thickness of the base plate and the number of bolts is attained, and the vibration-damping wall can be self-supported, so that the safety of construction work and workability are improved.
In addition, the method of installing a viscous vibration-damping wall in accordance with the present invention comprises the steps of: setting the lower-floor girder comprising the base-plate connecting hole portions and the flange connecting plates; setting at a predetermined position the upper-floor girder with which the viscous vibration-damping wall is integrated by connecting the intermediate plate to the gusset plate provided on the upper-floor girder and by connecting the housing to the upper-floor girder by means of a pair of temporarily connecting members for temporarily connecting the housing to the upper-floor girder; subjecting the base plate and the flange plates to friction-type high-strength bolted connection to the base-plate connecting hole portions and the flange connecting plates, respectively, of the lower-floor girder; and removing the temporarily connecting members from the housing and the upper-floor girder. Accordingly, handling is simple, sheer deformation of the viscous material can be prevented, and the movability of the vibration-damping wall is prevented.
The structure for installing a viscous vibration-damping wall in accordance with the present invention is characterized in that, in order to install a viscous vibration-damping wall constructed such that a housing with its upper end open is formed by uprightly setting a pair of steel-made side plates on a base plate and by disposing a pair of flange plates on both sides of the pair of side plates, an intermediate plate is inserted in the housing, and a viscous material or viscoelastic material is placed in its gap portion, a flange of a lower-floor girder is provided with base-plate connecting hole portions and a pair of flange connecting plates, and the base plate and the flange plates are connected thereto, and the intermediate plate is directly connected to a gusset plate fixed to a flange of an upper-floor girder. Accordingly, advantages are offered in that the top plate, the brackets, and the reinforcing rib plates at various portions which have been used in the building construction of the vibration-damping wall are made unnecessary, and the reduction of the thickness of the base plate and the number of bolts is attained, thereby making it possible to reduce the cost. Further, since the vibration-damping wall can be self-supported, an advantage can be demonstrated in that the safety of construction work and workability can be improved.
In addition, the method of installing a viscous vibration-damping wall in accordance with the present invention is characterized by comprising the steps of: setting the lower-floor girder; setting at a predetermined position the upper-floor girder to the gusset plate of which the intermediate plate is connected and with which the housing is integrated by means of a pair of temporarily connecting members; subjecting the base plate and the flange plates to friction-type high-strength bolted connection to the base-plate connecting hole portions and the flange connecting plates, respectively, of the lower-floor girder; and removing the temporarily connecting members from the housing and the upper-floor girder. Accordingly, advantages are offered in that handling can be made simple, shear deformation of the viscous material can be prevented, and the movability of the vibration-damping wall can be prevented.